'''http://luajit.org/%|%LuaJIT%|%''' is a remarkably fast [JIT] compiler that is source- and binary extension-compatible with [Lua] 5.1. 

** Creating a Tcl interpreter in LuaJIT **

[dbohdan] 2016-09-17: LuaJIT comes stock with a really nice http://luajit.org/ext_ffi.html%|%FFI library%|%. The code below is a translation of [PYK]'s example from the [Ffidl] page that shows how to create a Tcl interpreter in LuaJIT.

======
#! /usr/bin/env luajit

ffi = require("ffi")
-- The following line is for openSUSE Tumbleweed. If you run a different OS
-- you should probably replace it with something like
-- local tcl = ffi.load("tcl8.6")
local tcl = ffi.load("/usr/lib64/libtcl8.6.so")
ffi.cdef[[
typedef struct Tcl_Interp Tcl_Interp;
typedef struct Tcl_Obj Tcl_Obj;
typedef struct Tcl_DString {
    char *string;
    int length;
    int spaceAvl;
    char staticSpace[200];
} Tcl_DString;

Tcl_Obj *        Tcl_NewStringObj(const char *bytes, int length);
Tcl_Interp *     Tcl_CreateInterp(void);
char *           Tcl_GetCwd(Tcl_Interp *interp, Tcl_DString *cwdPtr);
int              Tcl_InterpDeleted(Tcl_Interp *interp);
char *           Tcl_GetString(Tcl_Obj *objPtr);
int              Tcl_EvalObjEx(Tcl_Interp *interp, Tcl_Obj *objPtr, int flags);
]]

local interp = tcl.Tcl_CreateInterp()
local script = tcl.Tcl_NewStringObj("puts [pwd]", -1)
tcl.Tcl_EvalObjEx(interp, script, 0)

local pwd = ffi.new("Tcl_DString")
tcl.Tcl_GetCwd(interp, pwd)
print(ffi.string(pwd.string))
======

** Discussion **

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